1. Field of the Invention
This invention relates generally to therapeutic beds, and more particularly to an improved rotating bed capable of placing a patient in a prone position.
2. Long-felt Needs and Description of the Related Art
Patient positioning has been used in hospital beds for some time to enhance patient comfort, prevent skin breakdown, improve drainage of bodily fluids, and facilitate breathing. One of the goals of patient positioning has been maximization of ventilation to improve systematic oxygenation. Various studies have demonstrated the beneficial effects of body positioning and mobilization on impaired oxygen transport. The support of patients in a prone position can be advantageous in enhancing extension and ventilation of the dorsal aspect of the lungs.
Proning has been recognized and studied as a method for treating acute respiratory distress syndrome xe2x80x9cARDSxe2x80x9d) for more than twenty-five years. Some studies indicate that approximately three quarters of patients with ARDS will respond with improved arterial oxygenation when moved from the supine to the prone position.
There are several physiological bases for patient proning. When a person lies flat in the supine position, the heart and sternum lie on top of and compress the lung volume beneath it. Moreover, the abdominal contents push upward against the diaphragm and further compress and increase the pressures on the most dorsal lung units, where perfusion (i.e., blood flow volume reaching alveolocapillary membranes) is greatest. In an ARDS patient, ventilation in these dorsal regions is inhibited by fluid and cellular debris that settle into the most dependent lung segments. Lung edema may further increase the plural pressures.in the most dependent regions. The combination of fluid accumulation with compression by the heart, sternum, and abdominal contents on the dorsal regions of the lung results in a significant ventilation-perfusion mismatch. Expressed more simply, the air entering the patient""s lungs is not reaching those parts of the lungs (the dorsal regions where perfusion is greatest) that most need it.
Flipping a patient into the prone position improves arterial oxygenation through several mechanisms. First, moving the fluid-filled lungs into a nondependent ventral position facilitates drainage of the fluid and cellular debris that had accumulated in and blocked ventilation to the dorsal regions of the lung. Second, the weight of the heart is supported by the sternum, rather than the lungs. When a patient is in the supine position, as much as 25-44% of the lung volume may be displaced by the heart, especially if the heart is enlarged due to cardiovascular disease. Rotating the patient into the prone position can reduce that displacement to as little as 1-4% of lung volume. Third, if the patient is supported in the prone position in a manner that allows the abdomen to protrude, then the abdominal contents no longer push upward onto the diaphragm to compress the lungs.
Proning minimizes the mechanical forces that pressurize distressed alveolar units into collapse, and can also recruit atelectatic but functional units for gas exchange. Proning also causes changes in pleural pressures, which encourages more uniform distribution of ventilation within the lungs. Proning often reduces the intrapulmonary shunt (defined as the portion of blood that enters the left side of the heart without exchanging gases with alveolar gases) and improves arterial oxygenation. The results of proning can be immediate, resulting in significantly improved oxygenation in as little as one hour.
Despite its promises, prone positioning has not been widely practiced on patients because, due to the inadequacies of prior art devices, it is a difficult and labor-intensive process. Logistically, moving a patient to the prone position using prior art technology requires careful planning, coordination, and teamwork to prevent complications such as inadvertent extubation and loss of invasive lines and tubes.
Even when precautions are taken, proning using prior art technology is fraught with potential complications. For example, it is difficult to provide cardiopulmonary resuscitation (xe2x80x9cCPRxe2x80x9d) to a patient lying in the prone position. Critical time may have to be spent recruiting a team of personnel to move the patient from the prone to the supine position before performing CPR. Accordingly, there is a need for a motor-operated proning device that will quickly rotate a proned patient from the prone position to the supine position. There is also a need for a system that enables a fast, one-step operation to cause the motor-operated proning device to rotate the patient back to a supine position.
A frequently cited complication with prone positioning is the development of pressure ulcers, especially on the forehead, chin, and upper chest wall. Immobility in the prone position can also result in breast and penile breakdown. Some of the most difficult areas to manage in the prone position are the head, face, eyes, and arms. Increased incidence of eye infection due to drainage, corneal abrasions, and even blindness caused by increased intra-ocular pressure have been reported as a consequence of prone positioning. Also, immobility and pressure on the arms have been reported to result in peripheral nerve injury and contractures. Accordingly, there is a need for a proning device that minimizes the risk of pressure-related complications.
Prone positioning using many prior art methods and devices has caused chest tubes, invasive lines, and infusions to become kinked. Worse, the rotation of a patient from the supine to the prone position on some beds has been reported to result in inadvertent extubation and decannulation, which can have catastrophic consequences. Accordingly, there is a need for a proning device with a patient line care management system that will minimize the risk of extubation, decannulation, or kinking of patient care lines.
Proning can also increase the risk of aspiration of gastric acid, food, or other foreign material into the lungs. Aspiration of gastric acid can result in severe pneumonia. Another complication, much more frequent than aspiration, is dependent edema. Most critically ill intensive care unit patients develop dependent edema. When moved into the prone position, the face is put into a dependent position, which often results in significant facial edema. Accordingly, there is a need for a proning device that will minimize aspiration and facial edema.
There are many prior art devices used to facilitate patient proning. One example is the Vollman Prone Device(trademark), made by the Hill-Rom Co., Inc.(copyright). The Vollman Prone Device comprises a set of foam pads to support the patient""s head, chest, and pelvis and which are secured to a patient with straps, belts, and buckles while the patient in the supine position. After the foam pads are secured, the patient is manually rotated into the prone position on a regular hospital mattress. Of course, no special device is needed to place a patient in the prone position. Towels, blankets, egg crate mattresses, and foam positioning pads can be used to help maintain proper alignment in the prone position.
One difficulty with devices such as the Vollman Prone Device is that several personnel are still required to turn the patient over. Moreover, medical personnel must revisit the patient frequently to turn the patient toward different positions to prevent pressure sores and other complications from developing.
To make it easier to turn a patient into the prone position, other prior art devices have been provided comprising a rotatable frame to rotate a patient into the prone position. The Stryker Wedge(copyright) Turning Frame, for example, comprises a rotatable frame having a supine support surface and a prone support surface in between which a patient is wedged. The frame is manually rotated into the desired position. But the frame still suffers several shortcomings. One of its shortcomings, as with other manually-operated prior art proning devices, is inadequate compliance by medical personnel. Because it is difficult and labor intensive to manually operate a proning bed, many doctors do not begin proning ARDS patients until late in the course of the patient""s disease process, after other recruitment measures have failed. However, there is a general consensus that if prone positioning is provided earlier, in the more exudative stages of ARDS, a patient will be more likely to respond positively. Accordingly, there is a need for a therapeutic bed that makes it simpler and less labor-intensive for medical personnel to prone a patient.
Another problem with manually-operated prior art beds such as the Stryker Wedge Frame is that unless manually rocked back and forth, patients will be left immobile, in a fixed position, for extended periods of time. Immobility leads to many of the complications discussed above that hinder the widespread adoption of prone positioning as a therapy for ARDS patients. Accordingly, there is a need for a therapeutic bed that provides not only prone positioning but also automated alternating side-to-side rotational therapy to intermittently relieve pressure from the dependent surfaces of the body.
Other beds made by Kinetic Concepts, Inc.(copyright), such as the TriaDyne(copyright) II, also facilitate prone positioning. Specially designed proning cushions have been provided to accommodate moving a patient to the prone position and maintaining the patient there. The TriaDyne""s low air loss pressure relief surface reduces the risk of certain complications like skin breakdown. While the TriaDyne has many benefits, its protocol calls for a team of about 5 to 8 people to move a patient from the supine to the prone position. One person should be assigned at the head of the bed to secure and manage the airway during the maneuver. The procedure also calls for the team to disconnect as many of the invasive lines as possible to simply the procedure, and then reconnect them when the patient has been placed in the prone position. Caution must be exercised with head positioning to prevent applying pressure directly to the eyes, ears, or endotracheal tube.
While it is possible to program the TriaDyne to perform continuous lateral rotation therapy while the patient is in the prone position, the TriaDyne is incapable of automatically rotating the patient from the supine to the prone position, and from there applying kinetic therapy. Moreover, the arc of rotation in the prone position is limited because of the absence of restraints to keep the patient centered on the bed while turning to a significant angle from the prone position. In practice, the range of motion in the TriaDyne is generally limited to no more than 30 degrees to the left and right of prone. The Centers for Disease Control (xe2x80x9cCDCxe2x80x9d) defines kinetic therapy as lateral rotation of greater than 40 degrees to the horizontal left and right, or an arc of at least 80 degrees.
Moreover, the TriaDyne and many other beds are not capable of rotation beyond 62 degrees from even the supine position, much less so from the prone position, because the beds lack restraints to hold the patient on the bed. It is the belief of the inventors that further therapeutic benefits could be obtained by rotating patients to angle limits beyond 62 degrees in either direction, to, for example, 90 degrees or more in either direction, in order to recruit further areas of a collapsed lung to participate in gas exchange, and also to further reduce pressure on the dorsal regions of the patient""s body. Accordingly, there is a need for a therapeutic bed that can automatically rotate a patient from the supine to the prone position and back, and that is capable of providing kinetic therapy (i.e., with an arc of at least 80 degrees) while still securing the patient to the center of the bed.
Another type of prone positioning bed comprises a base frame, a patient support platform rotatably mounted on the base frame for rotational movement about a longitudinal rotational axis of the patient support platform, and a drive system for rotating the patient support platform on the base frame. Such therapeutic beds are described in international patent applications having publication numbers WO 97/22323 and WO 99/62454. This type of bed is particularly advantageous for the treatment of patients with severe respiratory problems. Preferably, as described in publication number WO 99/62454, each end of the bed has a central opening at or near the longitudinal rotational axis of the patient support platform for efficiently managing the numerous patient care lines that are generally necessary for treating a patient on the patient support platform.
In the therapeutic bed of WO 99/62454, the central opening for receiving patient care lines at the head of the bed is provided by a continuous upright end ring, which also serves as a means for rotatably mounting the patient support platform on rollers. One drawback of such an arrangement is that the continuous end ring obstructs access to the head of the patient. Additionally, the initial placement of a patient on the bed requires disconnection of all patient care lines, and to remove a patient care line from the end ring requires that one end of the patient care line be unplugged from either the patient or the piece of equipment to which the line is attached, which can be very inconvenient and may jeopardize the patient, depending on the particular condition of the patient.
To retain a patient on the patient support platform in the prone position, the bed of WO 99/62454 has a pair of side rails fixedly mounted to the patient support platform in an upright position using stanchions and complementary sockets. A plurality of patient support packs are pivotally mounted on the side rails, and associated straps are buckled over the patient to hold the patient in place. Although the patient support packs may be flipped to the outside of the bed to uncover the patient in the supine position, the side rails remain upright and thus obstruct access to the patient in the supine position. To improve access to the patient in the supine position, it would be desirable to be able to move the side rails completely out of the way without removing them from the bed. Also, it would be advantageous to have a reliable way to ascertain whether the straps that buckle over the patient are properly tensioned to support the patient prior to moving the patient to the prone position.
One of the problems in the art of prone positioning therapeutic beds is to provide electrical connections to the bed for both the power and controller equipment that moves the bed and for the patient monitoring systems on the bed. To allow unrestricted rotation of the bed of WO 99/62454, electrical power has been provided by wire brushes at the interface between the rotating part of the bed and the nonrotating part of the bed. However, due to vibration and other abrupt movements, such wire brushes cause problems of electrical intermittence, which can be detrimental to the therapy of the patient. A direct, wired electrical connection would be preferable to eliminate such intermittence, provided that the wired electrical connection is capable of articulation during movement of the rotating part of the bed into the prone position.
Another problem in the field of prone positioning beds is to sufficiently support the head of a patient during rotation. In the past, elastic straps have been stretched across the patient""s head to secure the head to the patient support platform. However, such straps are generally uncomfortable for the patient and do not provide sufficient lateral support for the patient""s head. Additionally, such straps do not provide sufficient adjustability. It would be a significant improvement to provide a comfortable, adjustable head restraint that supports the patient""s head both laterally and vertically.
Typically, prone positioning beds have lateral support pads for supporting the sides or legs of the patient during rotation. It is known in the art for such lateral support pads to be laterally adjustable. For purposes of rotational stability, it is desirable for the patient to be centered on the patient support platform. Therefore, it would be an advancement in the art to provide adjustable lateral support pads that automatically center the patient on the patient support platform. In conjunction with automatically centering lateral support pads, it would also be an advancement to provide symmetric leg abductors.
As mentioned above, prone positioning beds preferably have a drive system for rotating the patient support platform on the base frame. However, such drive systems generally prevent manual rotation of the patient support platform by medical personnel. If a patient develops an emergency condition, such as the need for CPR, while the bed is in a position other than the supine position, the drive system must be used to rotate the bed back to the supine position before administering appropriate care to the patient. Because the drive systems are subject to mechanical and electrical failures, it would be advantageous to provide a back-up means for quick, manual rotation of the patient support platform in emergency conditions.
Prone positioning beds also preferably have a locking mechanism to lock the patient support platform in a desired rotational position. One known locking mechanism comprises a lock pin longitudinally mounted in the base frame that is insertable into a corresponding hole on the patient support platform. However, such lock pins may be jostled loose under the influence of vibration and other abrupt movements of the bed. It would be an improvement to provide a means to prevent accidental disengagement or locking of the lock pin.
It is also known in the art of prone positioning beds to provide a sensor for determining and controlling the rotational position of the patient support platform. As taught in WO 99/62454, the rotational position of the patient support platform may be monitored and controlled by a rotary opto encoder of the type described therein. However, such a rotary opto encoder is fairly cumbersome and must be reinitialized by moving to an index location in the event of power interruptions. It would be more desirable to provide a simple and reliable sensor that determines angle positioning relative to a fixed reference to control the rotational position of the patient support platform.
Medical personnel often consider it valuable to monitor a patient""s weight during the course of medical treatment. Many hospital beds have been designed and used that include weight scales to detect the combined weight of a patient and any accessories or equipment placed on the bed. Many of these beds sum the outputs of three or more load cells in analog and convert the summed analog signal to a digital value to detect the total weight borne by the load cells. Load cells, however, can malfunction, especially if they have experienced significant vibration or shock during transportation. However, it is difficult to detect when only one out of four or more load cells is malfunctioning if only the combined output is measured. Accordingly, there is a need for a weight monitoring system that evaluates the output of each load cell to detect malfunctioning load cells.
Because different doctors may develop different preferences for certain therapy settings, there is also a need for memory capabilities that enable medical personnel to program a course of therapy and to store it in memory for later retrieval and use. Because research studies on the benefits of kinetic therapy, prone positioning, or a combination of the two need to be based upon a consistent, pre-defined study-wide therapy protocol, there is a need for a data input interface that allows researchers to import a predefined protocol for operating the bed. Because it is important to monitor and record the effect that a course of kinetic, prone, or supine therapy, or some combination of them, has on a patient""s condition, there is also a need for a data output interface for relaying or permanently recording the course of therapy given to a patient. These are all long-felt needs that have been unmet or insufficiently met by prior art devices.
Through research and innovation, the inventors overcame numerous other challenges in developing the present invention. To prevent an operating system crash from causing unplanned rotation of the bed, which could be dangerous if a patient is not adequately secured, a redundant hardware and software design is needed so that no single hardware or software failure will result in a condition that would be harmful to the patient. There is also a need for a therapeutic bed that has a suitable user interface for operating, monitoring, and standardizing its various functions.
A therapeutic bed in accordance with the present invention is directed to solving the aforementioned problems. The bed is a prone positioning bed comprising a base frame, a patient support platform rotatably mounted on the base frame for rotational movement about a longitudinal rotational axis of the patient support platform, and a drive system for rotating the patient support platform on the base frame. The surface of the patient support platform is comprised of one or more honeycomb composite core panels, a lightweight yet strong material that is also radiolucent. A fan may be mounted on the patient support platform proximate the foot end ring to provide ventilation to a patient""s legs. A camera may also be mounted on the patient support platform proximate the head end ring to capture images of a patient""s face.
An upright end ring at the head end of the bed is split into an upper section and a lower section. The upper section is removable from the lower section to allow improved access to the head of the patient and to allow placement or removal of the patient from the bed by removal of patient care lines from the end ring without removing the patient care lines from the patient or the equipment to which the lines are attached. A slotted wheel may be used as an alternative to the upright end ring, where the wheel has an outer perimeter, a center, and a slot extending from the outer perimeter to the center for routing patient care lines. Likewise, at the foot end of the bed, an opening is provided that is of sufficient size to permit passing of various patient connected devices, such as foley bags, through the opening without disconnecting the devices from the patient.
The therapeutic bed is mounted on the base frame by placing the upright end rings on a plurality of rollers rotatably mounted on a plurality of respective axles protruding from the base frame. To account for minor tolerances in the manufacturing and assembly of the patient support platform or base frame, all but one of the rollers is laterally slidable along its respective axle.
Additionally, the bed is provided with pivotally mounted side rails that may be folded neatly out of the way underneath the patient support platform for improved access to the patient in the supine position. Straps are provided to secure the opposing side rails over the patient before rotation into the prone position. Preferably, a pressure-sensitive tape switch is mounted on the patient support platform adjacent each side rail. When the side rail straps are properly tensioned, the side rails engage the tape switches, which allows the patient support platform to be rotated into the prone position. Alternatively, the straps that secure the opposing side rails over the patient may be connected to the patient support platform with tension-sensitive strap connectors that provide an indication of whether the straps are sufficiently tensioned before the patient is rotated into the prone position. The tension-sensitive strap connectors provide both a visual indication and an electrical signal that may be used by a controller to control the rotation of the patient support platform.
The present invention also incorporates a direct, wired electrical connection to the patient support platform while still allowing full rotation of the patient support platform in either direction. The necessary electrical wires are housed within a chain-like cable carrier that is disposed within an annular channel attached to the patient support platform. An annular cover is installed adjacent the annular channel to retain the cable carrier within the annular channel, but the annular cover is not attached to the annular channel. Rather, the annular cover is attached to the nonrotating part of the bed. One end of the cable carrier is attached to the annular channel, and the other end is attached to the annular cover. The length of the cable carrier is sufficient to allow a full 360 degrees rotation of the patient support platform in either direction from 0 degrees supine flat while maintaining a direct electrical connection.
More preferably, the direct, wired electrical connection to the patient support platform may be provided with a flexible printed circuit board (PCB) in lieu of a chain-like cable carrier. The flexible PCB resides within an annular channel attached to the patient support platform, and an annular cover is fastened to a flange of the annular channel such that a gap exists between the annular channel and the annular cover around the outer periphery. One end of the flexible PCB is attached to the annular channel, which provides power and electrical signals to the rotating part of the bed, and the other end of the flexible PCB passes through the gap between the annular channel and the annular cover and is connected to the electrical apparatus on the nonrotating part of the bed. Like the cable carrier mentioned above, the flexible PCB has a length sufficient to allow a full 360 degrees rotation of the patient support platform in either direction while maintaining a direct electrical connection between the nonrotating and rotating parts of the bed. To ensure that the wired electrical connection is not articulated beyond its physical limit as a result of manually rotating the bed in the emergency backup mode, a mechanical stop is provided to limit rotation of the patient support platform to about 365 degrees. Sensors are provided to detect activation of the mechanical stop.
A pair of adjustable head restraints are provided for the therapeutic bed. Each head restraint, which is slidably mounted on transverse rails of the patient support platform, includes a clamping mechanism that fixes the position of the head restraint both vertically and laterally through the operation of a single lever. Each head restraint includes a pad that comfortably supports the front and side of the patient""s head.
As an alternative to the pair of adjustable head restraints, a head restraint apparatus is provided comprising a casing having a closed bottom end, an open top end, and an open front end. The casing, which is configured to substantially encompass the back and sides of a person""s head, encloses a cavity for receiving a person""s head resting in a supine position. A face piece configured to restrain at least a portion of the front of a person""s head is also provided for removable attachment to the top end of the casing. Optionally, the casing comprises left and right side members hingedly connected to a headrest member, so that a patient""s head can easily be placed on and removed from the casing by swinging the right and left side members outwardly from the casing. Openings are also provided in the right and left sides of the casing to provide access to a patient""s ears.
The casing may be pivotally mounted on a gas strut in order to enable limited movement of the head of a person being laterally rotated on the therapeutic bed. The casing may also be mounted on a guide member that mounts the casing to the bed and provides adjustable lateral and longitudinal positioning of the casing with respect to the bed.
A therapeutic bed in accordance with the present invention further includes a pair of symmetrically mounted lateral support pads or adductors that serve to automatically center the patient on the patient support platform. The lateral support pads are symmetrically mounted to a threaded rod that is transversely mounted to the patient support platform. The threaded rod has right-hand threads on one side and left-hand threads on the other side. One of the lateral support pads is mounted to the right-hand threaded portion of the threaded rod, and the other lateral support pad is mounted to the left-hand threaded portion of the threaded rod. By rotating the threaded rod in the desired direction, the lateral support pads may be moved symmetrically toward or away from the patient. Similarly, a preferred bed also includes a pair of leg abductors that are mounted with a threaded rod in like manner as the lateral support pads.
A motor and shaft brake are provided to safely drive the therapeutic bed of the present invention. The brake engages and impedes rotation of the motor""s shaft unless power is supplied to the brake. Therefore, if there is a fault in the system providing power to the therapeutic bed, the brake will arrest movement of the patient support platform.
The present therapeutic bed also preferably has a quick release mechanism for manually disengaging the patient support platform from the drive system. The quick release mechanism preferably comprises a manually operable lever and linkage that cooperate to push and pull a shaft to which a roller is mounted. The roller may thus be brought into or out of engagement with the belt of the drive system. When the roller is disengaged from the drive belt, the patient support platform may be manually rotated, which is useful in emergency conditions such as CPR.
The present bed further includes a lock pin mounted to the base frame that is insertable into a cooperating hole of a locking ring on the patient support platform to mechanically prevent rotation of the patient support platform. Preferably, the lock pin assembly incorporates a detent and a pair of proximity switches that indicate the position of the lock pin with respect to the locking ring and electrically control whether the patient support platform is allowed to rotate. The lock pin may be twistable to engage a protrusion on the lock pin with the patient support platform and thereby prevent retraction of the pin from its locked position.
The present invention also preferably includes an electrical angle sensor mounted to the patient support platform. A preferred angle sensor comprises an inclinometer that is sensitive to its position with respect to the direction of gravity. The output signal from the angle sensor may be calibrated for a controller of the drive system to control the rotational position of the patient support platform.
The present invention also preferably has a computer to operate the motor control circuitry in accordance with control signals received over a parallel cable from a computer mounted to the therapeutic bed. To prevent operating system crashes from causing the motor to operate unexpectedly by freezing the bits on the parallel cable, the motor control circuitry is preferably configured to require a code to be emitted by the computer over a separate serial bus to enable the motor control circuitry to operate the motor.
The present invention also preferably includes a weight monitoring system using a plurality of; load cells and circuitry (which may include computer hardware and software) capable of detecting failures in any one of the load cells. Each load cell produces an analog electrical output corresponding to a load borne by the load cell. The circuitry converts the analog electrical outputs of each of the load cells into a digital signal, and only then sums the digital signals together to calculate at least a portion of the bed""s weight. The circuitry further comprises memory for storing a patient""s weight trend data, calibration functions for determining the tare weight of the bed, a data entry function for entering a patient""s weight, and means for displaying a patient""s weight trend data.
A monitoring circuit is provided for the therapeutic bed to compute the total time a patient spent in kinetic therapy, prone kinetic therapy, prone kinetic therapy over an arc of at least 80 degrees, supine kinetic therapy, and supine kinetic therapy over an arc of at least 80 degrees.
A touch screen user interface is provided to monitor and control the operations of the therapeutic bed. The touch screen user interface guides a caregiver through a set of procedures for the caregiver to perform before rotating the patient support platform to the prone position. The user interface also provides programmable left angle limits, right angle limits, and a plurality of dwell times for a course of kinetic therapy. Alternatively, therapy settings can be imported through a data import interface and selected on the touch screen user interface. The touch screen interface also provides an emergency CPR button that, when selected, lowers both ends of the patient support platform and rotates it to the supine position. The touch screen interface also provides a hidden lockout button that, when selected, causes at least a portion of the touch screen interface to become nonresponsive to touch until a code is entered. The touch screen user interface also provides a data screen to display diagnostic information based upon readings from the plurality of sensors.
The therapeutic bed of the present invention is capable of rotating a patient from the supine position to the prone position and providing kinetic therapy in the prone position through an arc of rotation of up to approximately 730 degrees. Preferably, the patient support platform rotates at an angular velocity of no more than two degrees per second.
It is an object of the present invention to provide a therapeutic bed having a split end ring or slotted wheel at the head of the bed for improved access to the head of a patient lying on the bed and for placement or removal of the patient from the bed without disconnecting patient care lines from the patient.
It is another object of this invention to provide an opening at the foot of the bed having sufficient size to permit passing of patient connected devices, such as foley bags, through the opening without disconnecting the devices from the patient.
It is a further object of the present invention to provide a therapeutic bed having side rails that fold underneath the patient support platform of the bed for improved bedside access to the patient.
It is yet another object of this invention to provide a therapeutic bed with patient retaining straps having strap connectors that indicate whether the straps are sufficiently tensioned.
It is another object of the present invention to provide a therapeutic bed with side rails that are engageable with pressure-sensitive tape switches mounted to the patient support platform to indicate whether the straps on opposing side rails are properly tensioned.
It is still another object of this invention to provide a prone positioning therapeutic bed having a direct, wired electrical connection between the rotating part of the bed and the nonrotating part of the bed.
It is yet another object of this invention to mechanically limit rotation of the bed in either direction to one full 360xc2x0 turn plus about 50, and to electrically detect when one full turn has been reached.
It is a further object of this invention to provide a prone positioning therapeutic bed having a flexibly mounted head restraint apparatus to maintain proper patient alignment.
It is yet another object of this invention to provide a therapeutic bed having a pair of symmetrically mounted lateral support pads that serve to automatically center the patient on the patient support platform.
It is still another object of this invention to provide a prone positioning therapeutic bed with a patient support platform, a drive system for rotating the patient support platform, and a quick release mechanism for manually disengaging the patient support platform from the drive system to allow manual rotation of the patient support platform.
Another object of this invention is to provide a prone positioning therapeutic bed having a lock pin for mechanically preventing rotation of the patient support platform as desired.
Still another object of this invention is to provide a prone positioning therapeutic bed having a lock pin with cooperating proximity switches for electrically preventing rotation of the patient support platform as desired.
A further object of this invention is to provide a rotating therapeutic bed having a lock pin that is twistable to prevent disengagement of the lock pin.
Yet another object of this invention is to provide a therapeutic bed having a rotatable patient support platform with gravity-sensitive angle sensors for controlling the rotation of the patient support platform and for determining the longitudinal (Trendelenburg) angle of the patient surface.
Another object of this invention is to provide a therapeutic bed with foam having semi-independent pressure relieving pillars.
Still another object of this invention is to provide a user-friendly touch screen interface to control and monitor the operation of the therapeutic bed.
Further objects of this invention are to provide a system for monitoring a patient""s weight over time, detecting malfunctioning load cells, providing programmable therapy settings, and maintaining a log of past therapy provided.
Further objects and advantages of the present invention will be readily apparent to those skilled in the art from the following detailed description taken in conjunction with the annexed sheets of drawings, which illustrate the invention.